Compaction wheels



April 16, 1963 a. v. CHRISTENSEN COMPACTION WHEELS 5 Sheets-Sheet 1 Filed April '7, 1958 INVENTOR.

BRUCE V. CHRiSTENSEN ATTY A ril 16, 1963 B. v. CHRISTENSEN 3,085,483

COMPACTION WHEELS Filed April 7, 1958 5 Sheets-Sheet 2 INVENTOR.

BRUCE V. CHRISTENSEN Wax/oz:

ATTY.

April 1963 B. v. CHRISTENSEN 3,085,483

commcnon WHEELS Filed April 7. 1958 5 Sheets-Sheet 3 INVENTOR.

BRUCE V. CHRISTENSEN M CWJC ATTY.

A ril 16, 1963 B. v. CHRISTENSEN 3, 3

COMPACTION WHEELS Filed April 7, 1958 5 Sheets-Sheet. 4

INVENTOR.

BRUCE V. CHRISTENSEN Wayne/2% z/vfi:

ATTY.

A ril 16, 1963 B. v. CHRISTENSEN 3,085,483

COMPACTION WHEELS Filed April 7, 1958 5 Sheets-Sheet 5 BRUCE V. CHRQSTENSEN ATTY LO Q INVENTOR. Ll.

United States Patent 3,085,483 COMPACTIQN WHEELS Bruce V. Christensen, Berrien Springs, Mich., assignor to Clark Equipment Company, a corporation of Michigan Filed Apr. 7, 1958, Ser. No. 726,884 6 Claims. (Cl. 94--50) This invention relates to devices for compacting loose earth and the like, and more particularly to compaction wheels or rolls of the pad type.

It has been demonstrated previously that compaction wheels or rolls comprising a plurality of raised, out wardly curved, spaced apart pads making up a broken roll surface can be utilized for compacting loose earth and for other similar operations, such as a construction being in contrast to the solid roll type, sheeps foot type and other wheels and rolls of the prior art. Patent 2,754,734, Gardner, dated July 17, 1956, illustrates such a pad type roll. Gardner discloses a roll in which the total pad area pressing against the arc of contact with the material being rolled, when totalled across the width of the roll, remains constant as the roll progresses thereby providing constant pressure against the material being rolled.

The object of my invention is to provide a pad type roll with improved rolling characteristics which increases the compaction achieved for each pass of the roll, or, more explicitly, which increases the compaction achieved to a specified depth, for each pass of the roll.

Assuming that it were desired to increase the compaction per pass at a specified depth utilizing the structure taught by Gardner, there are three things which could be varied. These three possibilities are: (1) increasing the pad width, (2) reducing the ground contact area, or (3) increasing the weight on the roll.

Taking the possibility of increasing the pad width first, there is a limit to the extent to which the pad width can be increased without incurring disadvantages which overcome the advantage of increased compaction resulting from such increase in width. Some such disadvantages are discussed in the Gardner patent. Another disadvantage is that if the spaces between rows of pads are too small it may not be possible to use cleaners having teeth extending into such spaces, and it has been found that cleaners are necessary on pad type compactor rolls for some materials.

The second possibility-reducing the ground contactwould be accomplished by reducing the number of annular rows of pads on each wheel or roll, but this, of course, would have the obvious disadvantage of reducing the width covered by each pass and thus increasing the number of passes required to compact a given ground area. This possibility, that is, reducing the ground contact area, might also result in lack of sutficient buoyance, with the result that the pads would punch through the surface of the earth being compacted and provide a rough surface finish approaching that of the sheeps foot type compactor instead of a smooth finish.

With regard to the third possibility, that of increasing the weight of the machine, such a change ha the disadvantage of making the machine more costly and unwieldy, and it also has the disadvantage, mentioned previously in connection with possible reduction of ground contact area, of causing the pads to punch through the ground surface.

It will be thus understood that the object of my invention is to provide a pad type roll of improved operating characteristics which will provide more compaction per pass to a specified depth than would be provided by a roll of the Gardner construction on a machine of the same weight, pad width and area covered per pass.

In carrying out my invention in one form I provide "ice a compaction wheel or roll in which the pads of a plurality of annular rows on the wheel are so proportioned and arranged that as the wheel rolls over the surface of the ground the pad area in contact with the ground varies sharply at frequent intervals during a revolution and provides a tamping action due to the rapidly varying ground pressure. Such tamping action provides more compaction per pass to a specified depth thereby more effectively using the machine weight available than is possible with prior art rolls of the pad type, yet maintaining practically the same surface finish and other advantages. Reasonable buoyancy is maintained due to the rapid action, proper size and spacing of the pads and the increase in soil density proportional to the loading. Another wheel of the same general construction on the same machine may be constructed and arranged in such a manner as to pack the earth in the unpacked areas left by the spacing between rows of pads and between individual pads in a single row, in order to provide an even more uniformly and thoroughly compacted surface after one pass of the machine.

For a clearer and more complete understanding of my invention, reference should be had to the accompanying drawing in which FIGURE 1 is a side elevation of a rolling machine equipped with wheels embodying the present invention,

FIGURE 2 is a larger side elevational view of one of the front wheels of the machine in FIGURE 1,

FIGURE 3 is an end elevation of the wheel of FIG- URE 2, more specifically a view from the front of the right front wheel,

FIGURE 4 is a partial sectional view of the wheel of FIGURE 2, along the line 44 of FIGURE 2,

FIGURE 5 is an enlarged side elevational view of one of the rear whels of the rolling machine,

FIGURE 6 is an end elevation of the wheel of FIG- URE 5, and

FIGURE 7 is a partial sectional view of the wheel of FIGURE 5 along the line 7-7 of FIGURE 5.

Referring to the drawing, I have shown in FIGURE 1 a bulldozer machine 10 which is equipped also for use as a rolling machine. This machine comprises a body portion 11 housing a prime mover such as a diesel or other internal combustion engine, along with other components necessary for propelling the machine. It is equipped with a pair of front compaction wheels 12, only one of which is visible in this view, and a pair of rear compaction wheels 14, only one of which is visible. The machine 10 includes a bulldozer blade 18 although this blade forms no part of the present invention. The machine 10 also includes an operators station 20 and other components and feature necesary for a machine of this type.

In FIGURES 2, 3 and 4 of the drawing one of the front wheels 12 of the machine is illustrated in greater detail. Each wheel 12 includes a centrally located fiat ring or annular member 20 provided with openings 22 for lug bolts for connecting the wheel 12 to the hub of the rolling machine. It will be seen from FIGURE 4 that member 29 is the main structural member of the wheel and that it has a pair of cylindrical rings 24 and 26 welded or otherwise secured to the sides thereof. A plurality of spoke portions 28 are secured to one side of member 20 and to ring 24, while an equal number of spoke portions 30 are secured to the other side of member 20 and to ring 26, in alignment with spoke members 28 respectively. Portions 28 and 30 are rigidly secured to the intervening member 20 and the respective rings by welding or other equivalent means, and each portion 28 combines with its aligned portion 30 to form a complete spoke member 28, 30.

Spokes 28, 30 carry four outer rings 32, 34, 36 and 38,

and around the periphery of these rings are secured a plurality of spaced outwardly curved pads which I have indicated by the numerals 40, 42, 44 and 46 respectively, for the four rings. It will be observed that all pads 42 and 44 are identical, and that all pads 40 and 46 are identical, with a minor exception mentioned hereinafter, and that the pads on all rings are uniformly spaced around the respective rings. It will be noted also that pads 40 and 44 are in alignment transversely of the wheel while pads 42 and 46 are in alignment with each other but are staggered with respect to pads 40 and 44. All of the foregoing components maliing up the wheel are rigidly sccurcd together to form a compaction wheel or roller having a broken cylindrical compaction surface composed of raised outwardly curved individual pads.

The wheel illustrated in FIGURES 2, 3 and 4 is the right front wheel of the vehicle 10. The left front wheel is the mirror image of this wheel. It will be observed that in the front wheels the main structural member 20 is offset laterally somewhat from the center of the wheel.

FIGURES 5, 6 and 7 show the right rear wheel of vehicle 10, with FIGURE 5 being an enlarged side elevational view and FIGURE 6 an elevational view looking from the front of the vehicle while FIGURE 7 is a partial sectional view along the line 7--7 of FIGURE 5. The basic structure of this wheel is generally similar to that of the front wheel previously described and I, therefore, have indicated by the same identifying numbers the corresponding parts on this wheel. It will be observed that on this rear wheel the main supporting member 20 is located centrally of the whcel, so the rear wheel is somewhat different in this respect.

It will be observed that the pad arrangement of the rear wheel differs from the front wheel in that wider pads are used to form the. two outer rows of pads, and this has been indicated in FIGURES 6 and 7 by utilizing for the center rows of pads the same numerals 42 and 44 and for the wider outside pads the numerals 41 and 47. The rear wheel illustrated in the last three figures of the drawing also differs from the front wheel in that the outer compacting surface of the pads of the rear wheel is not a true cylinder but the rows of pads are tapered slightly, that is, the circumferential rows of pads have decreasing diameters away from the longitudinal axis of the vehicle, forming, in effect, a broken frustro conical surface. This can be seen in FIGURES 6 and 7 which are exaggerated from the actual construction in order to illustrate this feature. The line 49 in FIGURE 6 shows the outline of a true cylinder. The reason for this construction is that the rear wheels on machine 10 are the steering wheels, and as a result are arranged to have a small amount of camber. Making the outer compaction surface of the wheels slightly tapered compensates for this camber and provides for the ground engaging portion of the outer surface of the wheel to be approximately horizontal. It will be appreciated that the opposite rear wheel is tapered in the other direction to compensate for the opposite camber in that wheel.

It should be kept in mind in connection with compaction wheels or rolls of this type that the pads must be of such size and arrangement that there is sutficient pad area in contact with the ground at all times to buoy up the machine or float it on the surface of the ground, and not let the pads punch through the surface of the ground a considerable amount as with a sheeps foot roller, for example. On the other hand, there must be sutficient open space around the pads, and the pads must be raised sufficiently away from the main structure of the wheel, that the dirt being compacted does not clog the spaces around the pads and thus, in effect, produce a roller having a solid surface and having the consequent disadvantages inherent with solid rolls.

In one typical machine, in which the outside diameter of all wheels is approximately 60 inches, the pads 42 and 44 on both the front and rear wheels are four inches wide and approximately 1]. inches long measured along the outer curved ground engaging surface. In this same example, the pads 40 and 46 of the front wheels are 3 inches wide and approximately ll inches long, while the pads 41 and 47 of. the rear wheels are 5 inches by approximately ll inches. In these wheels the lateral spacing between rows of pads is 3 inches and 2 inches, being 3 inches for spaces A and B on wheel 12 and spaces E and F on wheel 14. and 2 inches for space C on wheel 12 and space D on w. eel 14; while the pads in all rows are uniformly spaced around the periphery and the spacing between adjacent individual pads in all rows is approximately 2% inches. Thus, the ground contacting area of the pads is approximately 52% of the total cylindrical area of the wheel including both pads and intervening spaces for the front wheel 12, while for the rear wheel 14 the percentage is approximately 57%. It will be appreciated that these percentages may be varied somewhat, depending upon the characteristics of the soil or other material being compacted, without departing from the present invention.

The improved compaction provided by these Wheels results from the numerous sharp changes in unit pressure on the ground as each wheel rolls over it. This will be understood by referring to the two dashed lines drawn transversely across the pads in FIGURE 3. Assume for purposes of illustration that the wheel is in a position such that the line 56 is directly at the bottom of its travel and, therefore, that the portions of the pads along this line, and also areas of the pad along both sides of the line, of course, are in contact with the ground. The pad area in contact with the ground at this time is thus a function of the width of all four pads.

Assume now that the wheel has rolled until the line 54 is directly at the bottom. At this time the pad area in contact with the ground is approximately half that at the time when line 56 was at the bottom of the wheel travel. There has been a sharp change in the unit pressure applied by the wheel on the gorund, and this produces a very desirable tamping action. In this particular example the change in unit pressure on the ground is approximately in the ratio of 1:2, although it is not exactly this in the usual case because of the fact that the wheels tend to sink into the ground more as the pressure increases which increases the contact area and decreases the unit pressure. It will be understood that with this design the unit pressure provided by each wheel varies continuously as the wheel rotates, thus providing a continuous tamping action as the rolling machine moves along the ground. This increases the efficiency of the compacting action, resulting in more compaction per pass to a given depth for a given machine weight than with prior art pad type compacting rolls.

The particular machine described and illustrated herein weighs approximately 34,500#. With the pad and Wheel dimensions given hereinbefore this provides a ground line pressure variations between a maximum of approximately 1080# per linear inch of wheel width and a minimum of 540# per lineal inch of pad width, assuming the load is divided among the Wheels in proportion to their ground contacting areas.

The front and rear wheels of the machine It complement each other in their compacting action inasmuch as they are in alignment on the respective sides of the machine and the pad patterns on the front and rear wheels are such that the pads on the rear wheel tend to cover the areas not compacted by the front wheels and vice versa providing thereby a move uniformly compacted area in the path of the machine.

It will be observed that the corners are cut off two of the pads in the left row in both FIGURES 3 and 6. This was not done to change the compacting action but rather was necessary with the wheels illustrated herein to permit the installation of cleaners which are not shown in this drawing. The absence of corners on these two pads does not affect significantly the compacting operation of these wheels. When reference is made in the subsequent claims to uniform pads or rectangular pads it should be understood that it is intended to cover also pads such as these with insignificant changes in the uniform pattern or from rectangular shape. Also, that individual pads are slightly curved, even though referred to herein, for clarity and convenience, in terms which ordinarily are applied to planar figures.

Similarly, it should be understood that where reference is made in the claims to an approximately cylindrical wheel, it is intended to cover minor variations from cylindrical such as the slightly tapered wheel-s 14.

Other means such as eccentric axles and vibrating means attached to the wheel or roller have been used previously to secure a tamping type action by a wheel or roller, but it has been found possible to secure superior tamping action with the construction disclosed and illustrated herein at far less cost than any prior art construction of which I am aware. Moreover, with this construction it is not necessary to design and construct a special machine for compacting operation only. The machine illustrated is a multi-purpose machine which is useful as well for other operations. It serves readily as a bulldozer or a towing tractor merely by removing the present compaction wheels and installing instead rubber tired wheels, an operation which can be performed in the field in a short time.

It will be readily understood that the present invention is not limited to the specific configuration, size and spacing of pads described and illustrated herein, but that one or more of these can be varied to suit specific conditions.

It will be understood also that whel I have disclosed a skeletal wheel construction and peripheral rings for mount ing the individual pads to raise them above the main portion of the wheel structure, that it is possible to use other means for raising the pads, such as individual spokes, for example, beneath each pad connecting it to the remainder of the wheel structure. It is essential, however, that the pads be raised to provide ready egress for dirt which passes through the spaces between pads during rolling. It is preferable that the wheel structure be of the skeletal type to further facilitate the disposal of such dirt; however, in some cases it may be desirable for the main body of the wheel to be hollow in structure making it possible to add water and thus increase the weight of the wheel and of the entire rolling machine.

Thus, while I have illustrated and described herein a preferred embodiment of my invention, it will be understood that modifications may be made. I intend to cover by the appended claims all such modifications falling within the true spirit and scope of my invention.

I claim:

1. A compaction wheel comprising four rows of raised annularity arranged outwardly curved thin ground engaging pads, all pads being of greater extent circumferentially than axially, the pads in one pair of the rows being of similar axial extent but of substantially different axial extent than the other pair of rows, and the individual rows of each pair being mutually staggered with respect to each other, whereby as the wheel rolls over the surface of the ground the pad area in contact with the ground varies sharply at frequent intervals during a complete revolution to provide a tamping action on the ground.

2. A compaction roll for mounting on a vehicle, comprising a central supporting structure, at least four annularly arranged rows of approximately rectangular outwardly curved thin ground engaging pads rigidly joined to the said supporting structure in raised relation to form an approximately cylindrical broken rolling surface, all of the said pads being of approximately equal extent circumferentially, the adjacent pads in all the said rows being uniformly spaced apart circumferentially and adjacent rows also being spaced apart axially by an amount not greater than the width of the narrowest of the adjoining pads, the pads in the two center rows being of approximately equal width, the pads in the two outer rows being approximately equal in width and different than the width of the said center rows, the space area between and around the said pads and within the margins of the cylinder equalling at least approximately 43% of the total cylindrical surface area, and one each the center and outside rows being staggered approximately half a pad length with respect to the other two rows whereby as the roll moves over the surface of the ground the pad area in contact with the ground varies sharply at frequent intervals during a complete revolution to provide tamping action on the ground.

3. A rolling machine having four compaction wheels, each wheel comprising a central supporting structure and four annularly arranged rows of approximately rectangular outwardly curved thin ground engaging pads rigidly joined to the supporting structure in raised relation to form an approximately cylindrical broken rolling surface, all of the said pads being of approximately equal extent circumferentially, the adjacent pads in all the said rows being uniformly spaced apart circumferentially and adjacent rows on each individual wheel also being spaced apart axially by an amount not exceeding the width of the narrowest of the adjoining pads, the two center rows of pads on all wheels being approximately equal in width, the two outer rows of pads on the wheels on one end of the machine being approximately equal to each other but less in width than the center rows, the outer rows of pads on the wheels at the other end of the machine being approximately equal to each other but wider than the said center rows, the wheels on each side of the machine being in alignment so that each pair of front and rear wheels cooperates in compacting the soil, and one row of pads of a certain width in each wheel being staggered approximately half a pad length with respect to the other duplicate row in that wheel whereby as the wheels roll over the surface of the ground the pad area on each wheel in contact with the ground varies sharply at frequent intervals to provide a tamping action on the ground.

4. A compaction roll for mounting on a vehicle, comprising a central supporting structure, four annularly arranged rows of approximately rectangular outwardly curved thin ground engaging pads rigidly joined to the said supporting structure in raised relation to form an approximately cylindrical broken rolling surface, the dimensions and spacing of said pads being proportional to the dimensions and spacing set out hereinafter for a typical roll approximately 60 inches in diameter: the pads of the two center rows approximately 11 inches circumferentially by approximately 4 inches axially and the two outer rows approximately 11 inches circumferentially by approximately 3 inches axially, the adjacent pads in all of the said rows being spaced apart approximately 2 inches, the said two center rows being spaced apart approximately 3 inches axially and one of the center rows being spaced approximately 3 inches axially from one of the outer rows and the other center row being spaced approximately 2 inches axially from the other outer row, the pads on one each of the center and outside rows disposed in axially alignment and the pads on the other two rows being staggered approximately half a pad length with respect to the first two said rows whereby as the roll moves over the surface of the ground the pad area in contact with the ground varies sharply at frequent intervals during a complete revolution to provide a tamping action on the ground.

5. A compaction roll for mounting on a vehicle, comprising a central supporting structure, four annularly arranged rows of approximately rectangular outwardly curved thin ground engaging pads rigidly joined to the said supporting structure in raised relation to form an approximately cylindrical broken rolling surface, the dimensions and spacing of said pads being proportional to the dimensions and spacing set out hereinafter for a typical roll approximately 60 inches in diameter: the pads of the two center rows approximately 11 inches circumferentially by approximately 4 inches axially and the two outer rows approximately 11 inches circumferentially by approximately inches axially, the adjacent pads in all of the said rows being spaced apart approximately 2%.; inches, the said two center rows being spaced approximately 3 inches axially and one of the center rows being spaced approximately 3 inches axially from one end of the outer rows and the other center row being spaced approximately 2 inches axially from the other outer row, the pads on one each of the center and outside rows disposed in axial alignment and the pads on the other two rows being staggered approximately half a pad length with respect to the first two said rows whereby as the roll moves over the surface of the ground the pad area in contact with the ground varies sharply at frequent intervals during a complete revolution to provide a tamping action on the ground.

6. A rolling machine having four compaction wheels, each wheel comprising a central supporting structure and four annularly arranged rows of approximately rectangular outwardly curved thin ground engaging pads rigidly joined to the supporting structure in raised relation to form an approximately cylindrical broken rolling surface, the dimensions and spacing of said pads being proportional to the dimensions and spacing set out hereinafter for typical wheels approximately 60 inches in diameter: for the two Wheels at one end of the machine the pads of the two center rows approximately 11 inches circumferentially by approximately 4 inches axially and the two outer rows approximately 11 inches circumferentially by approximately 3 inches axially, the adjacent pads in all of the rows of the said two wheels being spaced apart circumferentially approximately 2 inches, the said two center rows of each such Wheel being spaced apart approximately 3 inches axially and one of the center rows being spaced approximately 3 inches axially from one of the outer rows and the other center row being spaced approximately 2 inches axially from the other outer row; and for the two wheels at the other end of the machine the pads of the two center rows approximately 11 inches circumferentially by approximately 4 inches axially and the two outer rows approximately 11 inches circumferentially by approximately 5 inches axially, the adjacent pads in all of the said rows of the last-mentioned two wheels being spaced apart circumferentially approximately 2 inches, the said two center rows of each of the said lastmentioned wheels being spaced apart approximately 3 inches axially and one of the center rows being spaced approximately 3 inches axially from one of the outer rows and the other center row being spaced approximately 2 inches axially from the other outer row, the front and rear Wheels on each side of the machine being in alignment whereby the front and rear wheels of each pair cooperate With each other in compacting the soil, and one each of the center and outside rows of pads of each wheel being staggered approximately half a pad length with respect to the other two rows of that wheel whereby as the wheels roll over the surface of the ground the pad area on each Wheel in contact with the ground varies sharply at frequent intervals to provide a tamping action on the ground.

References Cited in the file of this patent UNITED STATES PATENTS 243,463 Schaefer June 28, 1881 1,432,984 Eburne Oct. 24, 1922 2,674,165 Paramythioti Apr. 6, 1954 2,754,734 Gardner July 17, 1956 2,895,390 Gardner July 21, 1959 FOREIGN PATENTS 734,479 Germany Apr. 16, 1943 591,437 Great Britain Aug. 18, 1947 OTHER REFERENCES Roads and Engineering Construction, page 90, October 1954. 

1. A COMPACTION WHEEL COMPRISING FOUR ROWS OF RAISED ANNULARITY ARRANGED OUTWARDLY CURVED THIN GROUND ENGAGING PADS, ALL PADS BEING OF GREATER EXTENT CIRCUMFERENTIALLY THAN AXIALLY, THE PADS IN ONE PAIR OF THE ROWS BEING OF SIMILAR AXIAL EXTENT BUT OF SUBSTANTIALLY DIFFERENT AXIAL EXTENT THAN THE OTHER PAIR OF ROWS, AND THE INDIVIDUAL ROWS OF EACH PAIR BEING MUTUALLY STAGGERED WITH RESPECT TO EACH OTHER, WHEREBY AS THE WHEEL ROLLS OVER THE SURFACE OF THE GROUND THE PAD AREA IN CONTACT WITH THE GROUND VARIES SHARPLY AT FREQUENT INTERVALS DURING A COMPLETE REVOLUTION TO PROVIDE A TAMPING ACTION ON THE GROUND. 